read_fits_partial

This routine reads unpolarised or polarised partial sky HEALPix map from a FITS file.
For more information on the FITS file format supported in HEALPix, including the one implemented in read_fits_partial, see https://healpix.sourceforge.io/data/examples/healpix_fits_specs.pdf.

Location in HEALPix directory tree: src/f90/mod/fitstools.F90 

FORMAT

call read_fits_partial( filename, pixel, cutmap, [header, extno] )

Arguments appearing in italic are optional.

ARGUMENTS

name & dimensionality	kind	in/out	description
filename(LEN=filenamelen)	CHR	IN	FITS file to be read from, containing a partial sky map
pixel(0:np-1)	I4B/ I8B	OUT	index of observed (or valid) pixels
cutmap(0:np-1,1:nc)	SP/ DP	OUT	value of unpolarised or polarised map for each observed pixel
header(LEN=80)(1:)	CHR	OUT	FITS extension header
extno	I4B	IN	extension number (0 based) for which map is read. Default = 0 (first extension).

EXAMPLE:

use healpix_modules
character(len=FILENAMELEN) :: file
integer(i4b) :: nmaps, polarisation, npix, nside
integer(i4b), allocatable, dimension(:) :: pixel
real(SP), allocatable, dimension(:,:) :: data
character(len=80), dimension(1:100) :: header=“”

file=“https://healpix.sourceforge.io/data/examples/partial_TQU.fits”
npix = getsize_fits(file, nmaps=nmaps, polarisation=polarisation)
print*, npix, nmaps, polarisation
allocate(pixel(0:npix-1))
allocate(data(0:npix-1,1:3))
call read_fits_partial(file, pixel, data, header=header)
print*,pixel(0), data(0,1:3)

reads a remote partial sky FITS file and prints the index and IQU values of the first pixel its contains.

MODULES & ROUTINES

This section lists the modules and routines used by read_fits_partial.

fitstools

module, containing:

printerror

routine for printing FITS error messages.

cfitsio

library for FITS file handling.

RELATED ROUTINES

This section lists the routines related to read_fits_partial

anafast

executable that reads a HEALPix map and analyses it.

synfast

executable that generate full sky HEALPix maps

getsize_fits

routine to know the size of a FITS file and its type (eg, full sky vs cut sky)

input_map

all purpose routine to input a map of any kind from a FITS file

output_map

subroutine to write a FITS file from a full sky HEALPix map

write_fits_partial

subroutine to write a partial map into a FITS file which can be read by read_fits_partial and/or input_map.